Audio
Tape -- Sound recording

Methods
and media for sound recording are varied and have undergone significant
changes between the first time sound was actually recorded for later playback
until now.

Bennett
(1980, p.114) describes the development of recording consciousness,
the consequence of "a society which is literally wired for sound" in which, according
to Middleton (1990, p.88) "this consciousness defines the social reality of popular
music." "Acoustic instruments and unamplified, 'pure'-tone singing can now not
be heard except as contrasts to more recent kinds of sounds, just as live perfromances
are inevitably 'checked' against memories of recordings," and "live performances
have to try to approximate the sounds which inhabit this consciousness."

Technology

Mechanical
Recording

The
first devices for recording sound were mechanical in nature.

In
1796 a Swiss watchmaker named Antoine Favre described his idea for what we now
call the cylinder musical box. This can be considered
an early method of recording a melody, although it does not record an arbitrary
sound and does not record automatically. "Playback" however is automatic.

The
Player piano was a device
that could playback a piano performance which had earlier
been mechanically recorded onto a piano roll.

The
first recording of sound waves

Leon
Scott invented the 'phonoautograph', the first device to record arbitrary
sound in 1857. It used a membrane (which vibrated
in response to sound) attched to a pen, which traced a line roughly corresponding
to the sound wave form on to a moving roll of paper. Although able to record sound,
the phonoautograph was unable to play back the recording; it was of little
use other than as a laboratory curiosity. (In one laboratory experiment, a phonoautograph
recording was photoengraved onto a metal plate, creating a groove, which was then
played back).

The
Phonograph and the Gramophone

The
phonograph built expanding
on the principles of the phonoautograph. Invented by Thomas Edison in 1877, the phonograph was
a device with a cylinder covered with a soft
material such as tin foil, lead, or wax on which a stylus drew grooves. The depth
of the grooves made by the stylus corresponded to change in air pressure created
by the original sound.
The recording could be played back by tracing a needle through the groove and
amplifying, through mechanical means, the resulting vibrations. A disadvantage
of the early phonographs was the difficulty of reproducing the phonograph cylinders
in mass production.

This
changed with the advent of the gramophone (phonograph in American English), which
was patented by Emile
Berliner in 1887.
The gramophone imprinted grooves on the flat side of a disc rather than the outside
of a cylinder. Instead of recording the varying the depth of the groove (vertically),
as with the phonograph, the vibration of the recording stylus was across the width
of the track ( horizontally). The depth of the groove remained constant. Berliner
called this audio disc a "gramophone record",
although it was often called a "phonograph record" in U.S. English.

Early
disc recordings and phonograph cylinders had about the same audio fidelity (despite
the cylinder's theoretical advantages of constant linear groove speed and greater
dynamic range of the hill-and-dale groove geometry). However, disc records were
easier and cheaper to mass produce. From the beginning, the flat disks were easily
mass-produced by a molding process, pressing a master image on a plate of shellac.

Originally,
cylinders could only be copied by means of a pantograph mechanism, which
was limited to making about twenty-five copies—all of significantly lower quality
than the original—while simultaneously destroying the original. During a recording
session, ten or more machines could be ranged around the talent to record multiple
originals. Still, a single performance could produce only a few hundred salable
copies, so performers were booked for marathon sessions in which they had to repeat
their performances over and over again. By the mid-1900s, successful molding processes
for cylinder recordings were developed, but by then disks had gained the ascendancy.

The
speed at with the disks were rotated was eventually standardized at 78 rpm. Later innovations allowed
lower rotations: 45 and 33!S rpm, and the material was changed to vinyl.

Both
phonograph cylinders and gramophone discs were played on mechanical devices most
commonly hand wound with a clockwork motor. The sound was amplified by a cone
that was attached to the diaphragm. The disc record largely supplanted the competing
cylinder record by the late 1910s.

The
advent of electrical recording in 1924 drastically improved the quality
of the recording process of disc records. Oddly, there was a period of nearly
five years, from 1925 to 1930, when the premiere technology
for home sound reproduction consisted of a combination of electrically recorded
records with the specially-developed Victor Orthophonic phonograph, a spring-wound
acoustic phonograph which used waveguide engineering and a folded horn to provide
a reasonably flat frequency response. Electrically-powered phonographs were introduced
c. 1930, but crystal pickups and electronic reproduction did not become common
until the late 1930s.

Magnetic
Recording

Magnetic
recording was demonstrated in principle as early as 1898 by Valdemar Poulsen in his
telegraphone.
Magnetic wire recording, and its successor, magnetic tape recording, involve the
use of a magnetizable medium which moves with a constant speed past a recording
head. An electrical signal, which is analogous to the sound that is to be recorded,
is fed to the recording head, inducing a pattern of magnetization similar to the
signal. A playback head can then pick up the changes in magnetic field from the
tape and convert it into an electrical signal.

With
the addition of electronic amplification developed by Curt
Stille in the 1920s, the telegraphone evolved into wire recorders which were
popular for voice recording and dictation during the 1940s and into the 1950s. The reproduction quality
of wire recorders was low, however — significantly lower than that achievable
with phonograph disk recording technology. Wire recorders could not prevent the
wire from undergoing axial twisting, and hence could not ensure that the wire
was oriented the same way during recording and playback. When oriented the wrong
way, high frequencies were reduced and the sound was muffled. The hysteresis of
the steel material resulted in nonlinear transfer characteristics, manifesting
as distortion. There were other practical difficulties, such as the tendency of
the wire to become tangled or snarled. Splicing could be performed by knotting
together the cut wire ends, but the results were not very satisfactory.

Early
tape recorders were first developed in Germany. On Christmas day 1932 the British Broadcasting
Corporation first used a tape recorder for their
broadcasts. The device used was a Marconi-Stille
recorder, a huge tape machine which used steel razor tape 3mm wide and 0.08mm
thick. In order to reproduce the higher audio frequencies it was necessary to
run the tape at a 90 metres per minute past the recording and reproducing heads.
This meant that the length of tape required for a half-hour programme was nearly
3 kilometres and a full reel weighed 25kg!

open
reel magnetic tape

Magnetic
tape recording as we know it today was developed in Germany during the late 1930s
by the C.
Lorenz company and by AEG . In 1938, S.
J. Begun left Germany and joined Brush
Development Company in the United States, where work continued but attracted
little attention.

Engineers
at AEG, working with the chemical giant I.G. Farben, created the world's
first practical magnetic tape recorder, the 'K1', which was first demonstrated
in 1935. During World War II AEG engineers
discovered the AC biasing technique. A high-frequency
signal, typically in the range of 50 to 150 kHz, is added to the audio signal
before being applied to the recording head. This means that the magnetization
is performed at levels in the most linear portion of the medium's transfer function.
Biasing radically improved sound quality and enabled them to develop their recorders
to new heights of technical excellence; by 1943 they had developed stereo tape
recorders.

During
the war, the Allies became aware of radio broadcasts
that seemed to be transcriptions (much of this due to the work of Richard_H._Ranger),
but their audio quality was indistinguishable from that of a live broadcast and
their duration was far longer than was possible with 78rpm discs. At the end of
the war, the Allied capture of a number of German Magnetophon recorders from Radio
Luxembourg aroused great interest. These recorders incorporated all of the key
technological features of analog magnetic recording, particular the use of high-frequency
"bias."

American
audio engineer John T. Mullin and entertainer
Bing Crosby were key players
in the commercial development of magnetic tape. Mullin served in the U.S. Army
Signal Corps and was posted to Paris in the final months of WWII; his unit was
assigned to find out everything they could about German radio and electronics,
including the investigation of claims that the Germans had been experimenting
with high-energy directed radio beams as a means of disabling the electrical systems
of aircraft. Mullin's unit soon amassed a collection of hundreds of low-quality
magnetic dictating machines, but it was a chance visit to a studio at Bad
Neuheim near Frankfurt while investigating
radio beam rumours, that yielded the real prize.

Mullin
was given two suitcase-sized AEG 'Magnetophon' high-fidelity recorders and fifty
reels of recording tape. He had them shipped home and over the next two years
he worked on the machines constantly, modifying them and improving their performance.
His major aim was to interest Hollywood studios in using magnetic tape for movie
sound recording.

Mullin
gave two public demonstrations of his machines, and they caused a sensation among
American audio professionals -- many listeners literally could not believe that
what they were hearing was not a live performance. By luck, Mullin's second demonstration
was held at MGM studios in Hollywood and in the audience that day was Bing Crosby's
technical director, Murdo Mackenzie. He arranged for Mullin to meet Crosby and
in June 1947 he gave Crosby a private demonstration of his magnetic tape recorders.

Crosby
was stunned by the amazing sound quality and instantly saw the huge commercial
potential of the new machines. Live music was the standard for American radio
at the time and the major radio networks didn't permit the use of disc recording
in many programs because of their comparatively poor sound quality. But Crosby
disliked the regimentation of live broadcasts, preferring the relaxed atmosphere
of the recording studio. He had asked NBC to let him pre-record his 1944-45
series on transcription discs, but the network refused, so Crosby had withdrawn
from live radio for a year, returning for the 1946-47 season only reluctantly.

Mullin's
tape recorder came along at precisely the right moment. Crosby realised that the
new technology would enable him to pre-record his radio show with a sound quality
that equalled live broadcasts, and that these tapes could be replayed many times
with no appreciable loss of quality. Mullin was asked to tape one show as a test
and was immediately hired as Crosby's chief engineer to pre-record the rest of
the series.

Crosby
became the first major American music star to use tape to pre-record radio broadcasts,
and the first to master commercial recordings on tape. The taped Crosby radio
shows were painstakingly edited (by hand) to give them a pace and flow that was
wholly unprecedented in radio. Mullin even claims to have been the first to use
"canned laughter"; at the
insistence of Crosby's head writer, Bill Morrow, he inserted a segment of raucous
laughter from an earlier show into a joke in a later show that hadn't worked well.

Keen
to make use of the new recorders as soon as possible, Crosby invested $50,000
of his own money into Ampex, and the tiny six-man concern soon became the world
leader in the development of tape recording, revolutionising radio and recording
with its famous Model 200 tape deck, issued in 1948 and developed directly from
Mullin's modified Magnetophones.

Working
with the brilliant Mullin, Ampex rapidly developed two-track stereo and then three-track
recorders. Spurred on by Crosby's move into television
in the early 1950s, Mullin and Ampex had developed a working monochrome videotape
recorder by 1950 and a colour recorder by 1954, both created to tape Crosby's
TV shows.

The
typical professional tape recorder of the early 1950s used ¼" wide tape on 10½"
reels, with a capacity of 2400 feet (731.5 metres). Typical speeds were initially
15 in/s (38.1 cm/s) yielding 30 minutes' recording time on a 2400 ft (730 m) reel.
30 in/s (76.2 cm/s) was used for the highest quality work.

Standard
tape speeds varied by factors of two. 15 and 30 in/s were used for professional
audio recording; 7½ in/s (19 cm/s) for home audiophile prerecorded tapes; 7½ and
3¾ in/s (19 and 9.5 cm/s) for audiophile and consumer recordings (typically on
7 in or 18 cm reels). 17/8; in/s (4.76 cm/s) and occasionally
even 15/16 in/s (2.38 cm/s) were used for voice, dictation,
and applications where very long recording times were needed, such as logging
police and fire department calls.

Multitrack
recording

The
next major development in magnetic tape was multitrack recording, in which the
tape is divided into multiple tracks parallel with each other. Because they are
carried on the same medium, the tracks stay in perfect synchronization. The first
development in multitracking was stereo sound, which divided the
recording head into two tracks. First developed by German audio engineers ca.
1943, 2-track recording was rapidly adopted for classical music in the 1950s because
it enabled signals from two or more separate microphones to be recorded simultaneously,
enabling stereophonic recordings to be made and edited conveniently. (The first
stereo recordings, on disks, had been made in the 1930s, but were never issued
commercially.) Stereo (either true, two-microphone stereo or multimiked) quickly
became the norm for commercial classical recordings and radio broadcasts, although
many pop music and jazz recordings continued to be issued
in monophonic sound until the
mid-1960s.

Much
of the credit for the development of multitrack recording goes to guitarist, composer
and technician Les Paul, who also designed the
famous electric guitar that bears his name. His experiments
with tapes and recorders in the early 1950s led him to develop the first 3-track
recorder, and his pioneering recordings with his then wife, singer Mary
Ford, were the first to make use of the technique of multitracking to record
separate elements of a musical piece asynchronously - that is, separate elements
could be recorded at different times, and Paul's invention enabled him to listen
to the tracks he had already taped and record new parts in time alongside them.

Paul's
invention was immediately taken up by Ampex, who soon produced a commercial 3-track
recorder. These proved extremely useful for popular music, since they enabled
backing music to be recorded on two tracks (either to allow the overdubbing of
separate parts, or to create a full stereo backing track) while the third track
was reserved for the lead vocalist. Three-track recorders remained in widespread
commercial use until the mid-1960s and many famous pop recordings -- including
many of Phil Spector's "Wall of
Sound" productions and early Motown hits -- were taped on Ampex
3-track recorders.

The
next important development was 4-track recording. The advent of this improved
system gave recording engineers and musicians vastly greater flexibility for recording
and overdubbing, and 4-track was the studio standard for most of the later 1960s.
Many of the most famous recordings by The Beatles
and The Rolling Stones
were recorded on 4-track, and the engineers at London's Abbey Road Studios
became particularly adept at a technique called "bouncing down", in which multiple
tracks were built up on one 4-track machine and then transferred (bounced down)
to one track of a second 4-track machine. In this way, it was possible to record
literally dozens of separate tracks and combine them into finished recordings
of great complexity.

All
of the Beatles classic mid-60s recordings, including the albums Revolver and Sgt
Pepper's Lonely Hearts Club Band, were recorded in this way. There were limitations,
however, because of the build-up of noise during the bouncing-down process, and
the Abbey Road engineers are still justly famed for the ability to create dense
multitrack recordings while keeping background noise to a minimum.

4-track
tape also enabled the development of quadrophonic sound, in which
each of the four tracks was used to simulate a complete 360-degree surround sound.
A number of albums including Pink Floyd's Dark Side of the Moon
and Mike Oldfield's Tubular
Bells were released both in stereo and quadrophonic format in the 1970s,
but 'quad' failed to gain wide commercial acceptance. Although it is now considered
a gimmick, it was the direct precursor of the surround sound technology that has
become standard in many modern home theatre systems.

In
a professional setting today, such as a studio, audio engineers may use
24 tracks or more for their recordings, one (or more) tracks for every instrument
played.

Magnetic
audio tape can be easily and inaudibly spliced. The combination of the ability
to edit via splicing, and the ability to record multiple tracks, revolutionized
studio recording. It became common studio recording practice to record on multiple
tracks, and mix down afterwards. The convenience of tape editing and multitrack
recording led to the rapid adoption of magnetic tape as the primary technology
for commercial musical recordings. Although 331/3; rpm
and 45 rpm vinyl records were the dominant
consumer format, recordings were customarily made first on tape, then transferred
to disk, with Bing Crosby leading the way in the adoption of this method in the
United States.

Analog
magnetic tape recording introduces noise, usually called "hiss", caused by the
finite size of the magnetic particles in the tape. There is a direct tradeoff
between noise and economics. Signal-to-noise ratio is increased at higher speeds
and with wider tracks, decreased at lower speeds and with narrower tracks.

By
the late 1960s, disk reproducing equipment
became so good that audiophiles soon became aware that some of the noise audible
on recordings was not surface noise or deficiencies in their equipment, but reproduced
tape hiss. A few companies starting making "direct to disk" specialty recordings,
made by feeding microphone signals directly to a disk cutter (after amplification
and mixing). These recordings never became popular, but they dramatically demonstrated
the magnitude and importance of the tape hiss problem.

audio
cassette

Prior
to 1963, when Philips
introduced the Compact audio cassette,
almost all tape recording had used the reel-to-reel
(also called "open reel") format. Previous attempts package the tape in a convenient
cassette that required no threading met with limited success; the most successful
was 8-Track cartridge used
primarily in automobiles for playback only. The Philips Compact audio cassette
added much needed convenience to the tape recording format and quickly came to
dominate the consumer market, although it was lower in quality than open reel
formats.

In the
1970s, advances in
solid-state electronics made the design and marketing of more sophisticated analog
circuitry economically feasible. This led to a number of attempts to reduce tape
hiss through the use of various forms of volume compression and expansion, the
most notable and commercially successful being several systems developed by Dolby Laboratories.
These systems divided the frequency spectrum into multiple bands and applied volume
compression/expansion independently to each band. The Dolby systems were very
successful at increasing the effective dynamic range and signal-to-noise ratio
of analog audio recording; to all intents and purposes, audible tape hiss could
be eliminated. The original Dolby A was
only used in professional recording. Successors found use in both professional
and consumer formats; Dolby B became almost universal for the compact cassette,
both prerecorded and for home use.

In
the 1980s, digital
recording methods were introduced, and analog tape recording was gradually displaced.
Digital audio tape never became important as a consumer recording medium partially
because of legal complications arising from piracy fears on the part of the record
companies. They had opposed magnetic tape recording when it first became available
to consumers, but the technical difficulty of juggling recording levels, overload
distortion, and residual tape hiss was sufficiently high that magnetic tape piracy
never became an unsurmountable commercial problem. With digital methods, copies
of recordings could be exact, and piracy might have become a serious commercial
problem. The introduction of the audio CD occurred about the same time and the
record companies heavily pushed this due to the fact it could not be home recorded.
However cd
recorders have since become available. Digital tape is still used in professional
situations and the DAT variant has found a home in computer data backup applications.

Recording
on Film

The first
attempts to record sound to an optical medium occurred around 1900. In 1906 Lauste
applied for a patent to record sound on film, but was ahead of his time. In 1923
de Forest applied for a patent to record to film. In 1927 the sound film The Jazz Singer was
released; while not the first, it made a tremendous hit and made the public and
the film industry realize that sound film was more than a mere novelty.

The
Jazz Singer used a process called Vitaphone, a process that involved
synchronizing the projected film to sound recorded on disk. It essentially amounted
to playing a phonograph record, but one that was recorded with the best electronic
technology of the time. Audiences used to acoustic phonographs and recordings
would, in the theatre, have heard something resembling 1950s "high fidelity."

In
the days of analog technology, however, no process involving a separate disk could
hold synchronization precisely or reliably. Vitaphone was quickly supplanted by
technologies which recorded a sound track optically directly onto the side of
the strip of motion picture film. This was the dominant technology from the 1930s
through the 1960s and is still in use as of 2004.

There
are two primary methods for optical recording on film. Variable density recording
uses changes in the darkness of the soundtrack side of the film to represent the
soundwave. Variable width recording uses changes in the width of a dark strip
to represent the soundwave.

In
both cases light that is sent through the part of the film that corresponds to
the soundtrack changes in intensity, proportional to the original sound, and that
light is not projected on the screen but converted into an electrical signal by
a light sensitive device.

In
the late 1950s the cinema industry, desperate to provide a theatre experience
that would be overwhelmingly superior to television, introduced wide-screen processes
such as Cinerama, Todd-AO, and CinemaScope. These processes
at the same time introduced technical improvements in sound, generally involving
the use of multitrack magnetic sound, recorded on an oxide stripe laminated
onto the film. In subsequent decades, a gradual evolution occurred with more and
more theatres installing various forms of magnetic-sound equipment.

In
the 1990s, digital systems were introduced and began to prevail. Ironically, in
many of them the sound recording is, as in Vitaphone, again recorded on a separate
disk; but now, digital processes can achieve reliable and perfect synchronization.

Digital
Recording

The
first digital audio recorders
were reel-to-reel decks introduced by companies such as Denon (1972), Soundstream
(1979) and Mitsubishi. They used a digital technology known as PCM recording. Within a
few years, however, many studios were using devices that encoded the digital audio
data into a standard video signal, which was then recorded on a U-matic or other
videotape recorder, using the rotating-head technology that was standard for video.
A similar technology was used for a consumer format, Digital Audio Tape
(DAT) which used rotating heads on a narrow tape contained in a cassette. DAT
records at sampling rates of 48kHz or 44.1kHz, the latter being the same rate
used on compact discs. Bit depth is 16 bits, also the same as compact discs. DAT
was a failure in the consumer-audio field (too expensive, too finicky, and crippled
by anti-copying regulations), but it became popular in studios (particularly home
studios) and radio stations. A failed digital tape recording system was the Digital Compact Cassette
(DCC).

Within
a few years after the introduction of digital recording, multitrack recorders
(using stationary heads) were being produced for use in professional studios.
In the early 1990s, relatively low-priced multitrack digital recorders were introduced
for use in home studios; they returned to recording on videotape.

In
the consumer market, tapes and gramophones were largely displaced by the compact
disc (CD) and a lesser extent the minidisc. These recording media
are fully digital and require complex electronics to play back.

Sound
files can be stored on any
computer storage medium.
The development of the MP3 audio file format, and legal issues
involved in copying such files, has driven most of the innovation in music distribution
since their introduction in the late 1990s.

As
hard disk
capacities and computer CPU speeds increased at the
end of the 1990s, hard disk recording
became more popular. At this writing (early 2005) hard disk recording takes two
forms. One is the use of standard desktop or laptop computers, with adapters for
encoding audio into two or many tracks of digital audio. These adapters can either
be in-the-box soundcards or external devices, either connecting to in-box interface
cards or connecting to the computer via USB or Firewire cables. The other common
form of hard disk recording uses a dedicated recorder which contains analog-to-digital
and digital-to-analog converters as well as one or two removable hard drives for
data storage. Such recorders, packing 24 tracks in a few units of rack space,
are actually single-purpose computers, which can in turn be connected to standard
computers for editing.

Technique

The
earliest methods of recording sound involved the live recording of the performance
directly to the recording medium. This was an entirely mechanical process, often
called "Acoustical recording". The sound of the performers was captured by a diaphragm
with the cutting needle connected to it. The needle made the groove in the recording
medium.

To make
this process as efficient as possible the diaphragm was located at the apex of
a cone and the performers would crowd around the other end. If a performer was
too loud then they would need to move back from the mouth of the cone to avoid
drowning out the other performers. In some early Jazz recordings a block of wood was
used in place of the bass drum.

The
advent of electrical recording made it possible to use microphones
to capture the sound of the performance. The leading record labels switched to
the electric microphone process in 1925, and most other record companies
followed their lead by the end of the decade. Electrical recording increased the
flexibity and sound quality. However, the performance was still cut directly to
the recording medium, so if a mistake was made the recording was useless.

Electrical
recording made it more feasible to record one part to disc and then play that
back while playing another part, recording both parts to a second disc. This is
called over-dubbing. The first commercially issued records using over-dubbing
were released by the Victor Talking
Machine Company in the late 1920s. However overdubbing was of
limited use until the advent of analogue audio tape. Use of tape overdubbing was
pioneered by Les Paul and is called 'sound
on sound' recording. Studios thus could create recorded "performances" that could
not be duplicated by the same artists performing live.

The
analogue tape recorder made it possible
to erase or record over a previous recording so that mistakes could be fixed.
Another advantage of recording on tape is the ability to cut the tape and join
it back together. This allows the recording to be edited. Pieces of the recording
can be removed, or rearranged. See also audio editing, audio mixing,
multitrack recording.

The
advent of electronic instruments
(especially keyboards and synthesisers), effects and
other instruments has led to the importance of MIDI in recording. For example, using
MIDI timecode, it is possible
to have different equipment 'trigger' without direct human intervention at the
time of recording.

In
more recent times, computers (digital audio workstation)
have found an increasing role in the recording studio, as
their use eases the tasks of cutting and looping, as well as allowing for instantaneous
changes, such as duplication of parts, the addition of effects and the rearranging
of parts of the recording.